Asymmetric Synthesis of Substituted anti-β-Fluorophenylalanines
摘要:
A range of substituted anti-beta-fluorophenylalanines was produced from the corresponding enantiopure a-hydroxy-beta-amino esters using a stereospecific XtalFluor-E promoted rearrangement procedure as the key step. The requisite substrates are readily produced via aminohydroxylation of an alpha,beta-unsaturated ester using our lithium amide conjugate addition methodology and, following rearrangement, deprotection of the resultant enantiopure beta-fluoro-a-amino esters gives the corresponding enantiopure anti-beta-fluorophenylalanines in good yield and high diastereoisomeric purity.
Asymmetric Synthesis of Substituted anti-β-Fluorophenylalanines
摘要:
A range of substituted anti-beta-fluorophenylalanines was produced from the corresponding enantiopure a-hydroxy-beta-amino esters using a stereospecific XtalFluor-E promoted rearrangement procedure as the key step. The requisite substrates are readily produced via aminohydroxylation of an alpha,beta-unsaturated ester using our lithium amide conjugate addition methodology and, following rearrangement, deprotection of the resultant enantiopure beta-fluoro-a-amino esters gives the corresponding enantiopure anti-beta-fluorophenylalanines in good yield and high diastereoisomeric purity.
Fluoro-Organocatalysts: Conformer Equivalents as a Tool for Mechanistic Studies
作者:Christof Sparr、Ryan Gilmour
DOI:10.1002/anie.201003734
日期:2010.9.3
Fluorine in charge! The fluorine–iminium ion gauche effect has been exploited in the design of conformational probes for organocatalysis (see scheme). Stabilizing hyperconjugative [σCH→σ*CF] and/or electrostatic [N+⋅⋅⋅Fδ−] interactions render the CF bond an excellent steering group for controlling molecular topology without introducing additional steric constraints.
Regiodivergent Nucleophilic Fluorination under Hydrogen Bonding Catalysis: A Computational and Experimental Study
作者:Matthew A. Horwitz、Alexander B. Dürr、Konstantinos Afratis、Zijun Chen、Julia Soika、Kirsten E. Christensen、Makoto Fushimi、Robert S. Paton、Véronique Gouverneur
DOI:10.1021/jacs.3c01303
日期:2023.5.3
regiochemical outcomes in nucleophilicfluorination reactions with alkali metal fluoride is a problem yet to be solved. Herein, two synergistic approaches exploiting hydrogen bonding catalysis are presented. First, we demonstrate that modulating the charge density of fluoride with a hydrogen-bond donor urea catalyst directly influences the kinetic regioselectivity in the fluorination of dissymmetric aziridinium